1. Field of Invention
This invention is for a welding helmet that significantly reduces exposure to welding fumes, contains a mechanism to cool the air drawn into the helmet and assists with the overall comfort of the welding task.
2. Background
Welding is considered a hot and dirty occupation by many practitioners who work at the profession. Recently, allowable levels of specific fume constituents resulting from arc welding are at such low levels that conventional means of staying below these levels such as keeping the welders head out of the fume plume are not sufficient. For example the current maximum recommended fume exposure level for some chrome (VI) compounds is 0.01 mg/m.sup.3. Even employing source capture may not be sufficient to assure welder exposure levels are below that maximum. Some fume constituents in steel welding may exceed newly reduced fume constituent levels. This may require a welder to use a respirator which makes the hot working environment even more uncomfortable and objectionable. Considering a significant amount of welding occurring in shops which are not cooled in warm weather the use of devices such as respirators makes the welding occupation less attractive. When welding in very toxic environments air has been delivered to welding helmets from an external source through a long hose. This is not practical for most welding applications.
3. Description of Prior Art
There have been some welding helmets that attempt to address some of the problems encountered while welding:    (a) Walters U.S. Pat. No. 3,548,415 (1968) entitled “Air Conditioned Helmet” describes a device that incorporates a fan enclosed in an open helmet, not one used for welding. He discusses several means of creating cooling such as gels, heat pipes and mentions but does not elaborate on the possible use of a thermal electric principle. As with many of the devices reviewed, this one relies on battery power. It also does not mention any means of reducing welding fume levels to a very low level.    (b) Greenlee in U.S. Pat. No. 3,535,707 (1970) entitled “Welding Helmet and the Like,” describes a welding helmet with a fan in the front which draws air from the rear of the helmet. The back of this helmet, as with most welding helmets, is open. At the very low allowable concentrations of some welding fume constituents this approach would not provide sufficiently low fume breathing air in most welding applications.    (c) Martin, et al in a US patent application 2007/0056073 entitled “Modular Auto-Darkening Welding Filter,” discusses one of the optional features of the present invention, that of using external knobs to adjust some of the functions of the helmet. External adjustment of auto-darkening welding lens shade is common to some commercial welding helmets.    (d) Apisdorf in U.S. Pat. No. 5,193,317 (1993) entitled “Helmet-Mounted Air System for Personal Comfort,” describes the use of a helmet that incorporates a thermal electric device to cool the air brought in by a fan. He discusses the small amount of cooling 0.4 to 4 degrees Centigrade the device provides and justifies it as being sufficient to cause comfort. Flow rates are also quite low, approximately 1 to 4 m3/minute. It appears he is justifying these low levels of flow and small amount of cooling to justify his device being powered by a battery placed on a belt.    (e) Buckman in U.S. Pat. No. 7,534,005 (2009) entitled “Welding Helmet,” describes the use of multiple fans and a filter. However, the claims describe a conventional welding helmet with only front and sides, not the back or the top of the welders head covered. There is no mention of a cooling device of the thermal electric type or of any type that would significantly improve the welder's temperature environment.